And I'm Steve Inskeep in Las Vegas, where the traffic continued all night last night along the Las Vegas Strip. Many of the brilliant lights for which the Strip is known burned all night, although the replica Eiffel Tower at the Paris casino, which is visible out a window to my left here, went dark all night to mark Sunday's mass shooting. The fountains of the Bellagio hotel went still. From the first gunshots on Sunday night, police faced a series of questions about the shooter. First, how to stop him. Next, why he did what he did. NPR's law enforcement correspondent Martin Kaste is here with us in Las Vegas. Good morning, Martin.

MARTIN KASTE, BYLINE: Good morning.

INSKEEP: So what more is known about Stephen Paddock, the guy who opened fire from the Mandalay Bay hotel down the street?

KASTE: Well, any hope for a - excuse me - for a motive is sort of elusive right now. This man is not fitting any of the common profiles we come to expect for perpetrators of these mass shootings. He's an older man. He apparently had enough money, apparently well-to-do, actually, from real estate investments. He didn't have any known sort of religious affiliation that might have driven him to this. There was no sort of cause that he'd espouse that anyone knew about. But we - one thing we do know about him, besides the fact that he liked to gamble and he lived here in Nevada, is that he had a lot of weapons. The police still working through that room that he was shooting out of at Mandalay Bay say they've found 23 firearms in that hotel suite. There were another 19 guns in his house in Mesquite, Nev., about an hour from here. So a lot of weaponry that burst onto the scene all at once for everyone to see on that Sunday night there. They also found in that room, though, a computer and some electronic media. They're still working through that. So maybe there's some hope for some insight on why he did this once they've gotten through that.

INSKEEP: And - and we should remember just what we've learned from past mass shootings, very often you have an individual who is in some way troubled, they make up their mind to do this and they come up with the motive along the way. The motive is almost incidental to the fact that they're on their way to committing some horrible act.

KASTE: Exactly. Hard - hard to pin this down. You know, one thing about this situation, though, is we don't know a lot about him, but we do know a lot right now about what happened that night because of recordings of the police dispatch radio. I've been going through some of those recordings trying to reconstruct a timeline, and it's riveting to listen to the way these police here in Las Vegas responded to what looked like an act of war. It - what was amazing is it was shortly after 10 o'clock, about 10:07, when the first shots rang out. Without - within a few seconds, almost a minute, they had already sort of narrowed down where this was coming from. Take a listen to this first piece of tape of the cops reacting there on the ground looking up at the hotel.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED POLICEMAN #1: One-seven-nine. 10. Vegas. Coming from upstairs at the Mandalay Bay. Upstairs at the Mandalay Bay, halfway up. I see the shots coming from Mandalay Bay. Halfway up.

KASTE: So you can hear them there on the radio talking to each other. And right from the start, they're already referring to this as fully-automatic gunfire. To their ears, there was no doubt this was automatic weapons.

INSKEEP: And they're saying coming from upstairs, Mandalay Bay. They were figuring out where the shots were coming from, which is not easy the way shots echo around an area like this. So - so how long then did it take police to zero-in on the exact location of the shooter once they knew approximately where he was?

KASTE: It was remarkably quick. It was within about six minutes. There's an officer on the radio saying that he's already up on the 31st floor and he thinks the shooter is on the floor above him, which was correct. And just a few minutes later, they've even figured out which room he's in. So you can hear them on this radio open-channel whispering to each other as they approach that floor and clear it out and get ready to breach the door.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED POLICEMAN #2: I need everybody in that hallway to be aware of it and get back. We need to pop this and see if we get any type of response from this guy, to see if he's in here or if he's actually moved out somewhere else.

KASTE: And while they're whispering there on that very same open radio channel, you can hear other officers jumping in sort of with, you know, a lot more stress in their voice from the chaos down on the ground. At one point, one officer says some of the panicked citizens are trying to steal weapons from the squad cars because they're so terrified.

(SOUNDBITE OF ARCHIVED RECORDING)

UNIDENTIFIED POLICEMAN #3: Advise all units to have their vehicles locked. People are going in to them trying to grab shotguns.

UNIDENTIFED POLICEWOMAN: All units make sure your vehicles are locked. Citizens are trying to grab shotguns.

INSKEEP: Somehow, despite the chaos on the street, police need to stay focused, I guess, at this point on trying to get to the shooter on the 32nd floor.

KASTE: Yeah, and that's what they're doing. They even remind each other that, you know, the newest training for these active situations, active shooter situations, is to get there to the source of the danger.

INSKEEP: Get there to the source of the danger. So what else do you hear in these dispatch tapes, Martin?

KASTE: Well, this is clearly, like so many large police departments in this country, a department that's thought this through, that had sort of the sense that you have to go into the warm zone, as they sometimes call it, with paramedics, with first responders. Even when there's still a danger of being shot, there is a sense that you have to try to eliminate the shooter as quickly as possible. There was something of a lag. They didn't breach that door, actually, for a good hour or so after the first shooting. And at that point, he'd stopped shooting, possibly was already dead. But they certainly went in fast then waited for backup.